Synthesis of brass nanowires and their use for organic photovoltaics

Preponderant electric conductivity, high transmittance properties, and large natural abundance of its main component are striking features of copper nanowire (Cu NW)-based thin films. Because they are easily synthesized via low-cost solution-based processes, copper nanowires are considered an affordable next-generation conductor for transparent electrodes. Copper nanowire applications are expected to become more popular over the next decade. However, copper nanowire itself has a tremendously high surface-to-volume ratio and an abundance of surface atoms which lead to its high reactivity with the external environment. This reactivity presents a challenge for the improvement the long-term stability of copper nanowires, as it directly affects their applications. This novel study demonstrates a process to protect copper nanowires with an ultrathin stable brass layer-Cu/Brass NWs. The final product exhibited a high performance comparable to commonly used electrodes with a low sheet resistance of 30 Ω/sq at 89% transparency. Moreover, the Cu/Brass NWs resisted oxidation corrosion as the amplitude resistance fluctuated only around 3 Ω/sq for 30 days. For performance verification, an organic solar cell was fabricated using a Cu/Brass NW-based transparent electrode. It yielded an efficiency of 5.85%, reaching nearly that of a conventional cell using indium tin oxide. This demonstrates that Cu/Brass NWs are very promising for future application in low-cost optoelectronic devices.